For a construction machine connected to an external server via an external communication means, a method disclosed in Patent Literature 1 has conventionally been known as a method for rewriting an in-vehicle program into a new program, for the purpose of updating for example. In this method, when an on-board controller selects a rewrite mode based on a rewrite command from a server, the current program is rewritten by an update program sent from the external server via the external communication means to the on-board controller.
According to Patent Literature 1, data transmission from the server and rewriting of the program are directly and continuously performed on an on-board controller as described above, which typically requires a long period of time for updating.
This is likely to result in incomplete updating caused by hung-up or the like which happens by a long use of an “external communication means”, which inherently has a risk of abnormal communication and reduction in the communication speed.
Besides, the time required for updating the program, that is, the period of time in which a user cannot work before completion of updating, is long, and this results in low work efficiency.
Moreover, in the method disclosed in Patent Literature 1, updating is aborted if rewriting has not been completed within a set time period, and the program is written again into the pre-update current program. In such a case, the binding time extends by the time period required to write the program again into the pre-update current program, which further worsens the work efficiency.